GB1097214A - Modulating system - Google Patents
Modulating systemInfo
- Publication number
- GB1097214A GB1097214A GB12116/65A GB1211665A GB1097214A GB 1097214 A GB1097214 A GB 1097214A GB 12116/65 A GB12116/65 A GB 12116/65A GB 1211665 A GB1211665 A GB 1211665A GB 1097214 A GB1097214 A GB 1097214A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signals
- modulation
- signal
- carrier
- video
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03C—MODULATION
- H03C1/00—Amplitude modulation
- H03C1/36—Amplitude modulation by means of semiconductor device having at least three electrodes
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/64—Circuits for processing colour signals
- H04N9/65—Circuits for processing colour signals for synchronous modulators
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/64—Circuits for processing colour signals
- H04N9/66—Circuits for processing colour signals for synchronous demodulators
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Amplitude Modulation (AREA)
- Processing Of Color Television Signals (AREA)
Abstract
1,097,214. Amplitude modulation; transistor amplifying circuits; colour television. RADIO CORPORATION OF AMERICA. March 22, 1965 [April 3, 1964], No. 12116/65. Headings H3R, H3T and H4F. In a modulation system producing unwanted output signals at the modulation frequency and at the carrier frequency, the modulation signal is eliminated by combining with it a modulation signal of opposite polarity, and the carrier signal is eliminated by deriving from it a D.C. control signal which is fed back and combined with the modulation frequency. In a colour television system, Q and I video signals are separately amplified in amplifiers 6, 8 and are fed to chopper modulator 13, 14 where they are modulated with sub-carrier signals having the same frequency and quadrature related phases. The resulting outputs are added and fed to a mixing amplifier 23 which produces an output modulated in amplitude and phase. The Q and I video signals are also added and phase inverted in unit 12 to provide a video signal at the input of the mixing amplifier 23 which can be adjusted to cancel out any video frequency signals present at the modulator outputs. Any residual signal at sub-carrier frequency is fed via limiter 27 to a sampling circuit where it is sampled, during periods when no modulation is present, to produce D.C. signals proportional to the relative levels of I and Q sub-carrier components. These signals are then combined with the respective video signals so as to produce signals at the modulator outputs which cancel the residual sub-carrier signals. The required modulated signal, comprising only sidebands is fed to output 26. The video amplifier comprises transistors 4, 5 with negative feedback applied from the emitter of transistor 5 to the base of transistor 4 via a resistor (2400 Q).
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US357043A US3317661A (en) | 1964-04-03 | 1964-04-03 | Color television modulating system |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1097214A true GB1097214A (en) | 1968-01-03 |
Family
ID=23404066
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB12116/65A Expired GB1097214A (en) | 1964-04-03 | 1965-03-22 | Modulating system |
Country Status (3)
Country | Link |
---|---|
US (1) | US3317661A (en) |
DE (1) | DE1276135B (en) |
GB (1) | GB1097214A (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3739280A (en) * | 1970-12-10 | 1973-06-12 | R Grodinsky | Controlled carrier amplitude modulated signal transmitting and receiving system |
US3721755A (en) * | 1971-03-29 | 1973-03-20 | Telemation | Color television encoder modulator |
US4100568A (en) * | 1976-05-05 | 1978-07-11 | Commercial Electronics, Inc. | Color television encoder signals |
DE3328025C1 (en) * | 1983-08-03 | 1985-02-14 | Institut für Rundfunktechnik GmbH, 8000 München | Color carrier modulator |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR963714A (en) * | 1944-05-03 | 1950-07-19 | ||
US2835730A (en) * | 1955-01-28 | 1958-05-20 | Rca Corp | Automatic balancing of color subcarrier balanced modulator |
US3040274A (en) * | 1959-12-28 | 1962-06-19 | Gen Electric | Balanced modulator |
-
1964
- 1964-04-03 US US357043A patent/US3317661A/en not_active Expired - Lifetime
-
1965
- 1965-03-22 GB GB12116/65A patent/GB1097214A/en not_active Expired
- 1965-03-31 DE DER40265A patent/DE1276135B/en active Pending
Also Published As
Publication number | Publication date |
---|---|
DE1276135B (en) | 1968-08-29 |
US3317661A (en) | 1967-05-02 |
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